>>15791446
If you want to dip your toe in homebrew, you're better off making a romhack first to see if the process is right for you. Super Mario World, Super Metroid, and Pokemon (Gen 1-3) have dedicated communities that reverse engineered their own tile editors and level editors. However, the BIGGEST problem with ROMhacks is that, since you're working with hex, changing functions for physics and AI is difficult, so you can't have truly custom bosses without busting your balls.
However, if you can handle more than sprite editing for JRPGs, then proceed to look into the devkits that the developers used.for some of these consoles, mostly in DOS/Silicon Graphics. For example, GEMS is useful for making Genesis midis from scratch in DOS, or using KallistiOS for the heavy lifting. Some consoles are unlucky, so the only thing you may have is notepad++ while working in assembly, and working to get the game even to run.
If you got the 'tism for it, go ahead, but if you just want to make something as fast as possible you could use Godot instead, it can handle 2D graphics all the same without the RAM management. Hell, even La-Mulana (original version) didn't need original hardware to achieve what it was going for (emulating the MSX2 experience natively on PC), so it's all about how you tweak it.